The present invention relates to an operation control apparatus for a robot mechanism.
A conventional control apparatus of the type described employs for controlling a robot both an orthogonal coordinate system, which relates directly to the environment around the robot, and a link coordinate system, which relates directly to the robot mechanism itself. The conventional control apparatus must include a device for transforming between these coordinate systems using coordinate transformation equations and inverse transformation equations.
FIGS. 1A and 1B of the accompanying drawings illustrate two robots having different link mechanisms. FIG. 1A shows a vertical six-axis link or articulation robot including a drive motor 1M for bodily turning the robot. The drive motor 1M is coupled through a speed reducer 1G to a robot turntable 1. The robot also has a drive motor 2M for driving an arm 2 through a speed reducer 2G, a motor 3M for driving an arm 3 upwardly and downwardly through a speed reducer 3G, a motor 4M for rotating an arm 4 through a speed reducer 4G, a motor 5M for bending an arm 5 through a speed reducer 5G, and a motor 6M for swiveling an arm 6 through a speed reducer 6G.
FIG. 1B illustrates a vertical five-axis link or articulation robot, The robot has a drive motor 7M for rotating a turntable 7 through a speed reducer 7G, a drive motor 8M for moving an arm 8 back and forth through a speed reducer 8G, and a drive motor 9M for enabling parallel links 12 and 13 to move an arm 9 upwardly and downwardly through a speed reducer 9G. The robot also includes drive motors 10M and 11M for moving arms 10 and 11 through speed reducers 10G and 11G, with the drive motor 10M being connected through parallel links 14, 15 and 16 to the turntable 7 and with the drive motor 11M also being connected to the turntable 7 through the same links 14, 15 and 16.
Coordinate systems inherent to the robot mechanisms shown in FIGS. 1A and 1B, that is, the most convenient coordinate system for the particular mechanism at hand, are shown respectively in FIGS. 2A and 2B. In FIGS. 2A and 2B, those elements denoted by reference numerals 1 through 11 correspond respectively to the arms 1 through 11 illustrated in FIGS. 1A and 1B. Designated by J.sub.Mn (n=1 through 6) are angles of rotation of the motors from corresponding reference points.
In the mechanism of FIG. 1A, the motor for driving the arm 3 is mounted on the arm 2, and thus the position of the arm 3 is dependent on the attitude of the arm 2. Likewise, the motors for driving the arms 5 and 6 are mounted on the arm 4, and the positions of the arms 5 and 6 are thus dependent on the attitude of the arm 4. Accordingly, a coordinate system inherent to the robot mechanism shown in FIG. 1A has reference points for the angles J.sub.M3 and J.sub.M5, on extensions of the arms 2 and 4, respectively, as illustrated in FIG. 2A.
With the robot mechanism of FIG. 1B, the arm 9 remains fixed in position as the attitude of the arm 8 varies. The driver motors 10M and 11M are also free from any influence of the attitude of the arm 9 through the link mechanism. Therefore, a coordinate system inherent to the robot mechanism shown in FIG. 1B has reference points for the angles J.sub.M2, J.sub.M3 and J.sub.M4 along the direction of the Z-axis.
As described above, the most convenient coordinate system is determined entirely by the arrangement of the robot mechanism. Therefore, the coordinate transformation equations for transforming from the orthogonal coordinate system at the outside controller of the robot into a coordinate system which uses the motors as references, and the corresponding inverse coordinate transform equations, vary from robot to robot. It has been conventional practice to develop and design a new control apparatus for each respective new robot type.